Added type annotations

.gitignore

@@ -21,6 +21,9 @@
 # Pycharm files
 /.idea
 
+# Type check files
+/.mypy_cache
+
 # Test coverage files
 .coverage
 tests-coverage.txt

.travis.yml

@@ -5,7 +5,7 @@ dist: bionic
 jobs:
   include:
   - name: "Pylint on Ubuntu Bionic (20.04) (Docker) with Python 3.8"
-    env: [TARGET="pylint", UBUNTU_VERSION="20.04"]
+    env: [TARGET="lint_and_type_check", UBUNTU_VERSION="20.04"]
     group: edge
     language: python
     python: 3.8

config/travis/install.sh

@@ -37,9 +37,9 @@ then
 	else
 		RPM_PACKAGES="";
 
-		if test ${TARGET} = "pylint";
+		if test ${TARGET} = "lint_and_type_check";
 		then
-			RPM_PACKAGES="${RPM_PACKAGES} findutils pylint";
+			RPM_PACKAGES="${RPM_PACKAGES} findutils pylint python3-mypy";
 		fi
 		RPM_PACKAGES="${RPM_PACKAGES} python3 ${RPM_PYTHON3_DEPENDENCIES} ${RPM_PYTHON3_TEST_DEPENDENCIES}";
 	fi
@@ -87,9 +87,9 @@ then
 		then
 			DPKG_PACKAGES="${DPKG_PACKAGES} sudo";
 
-		elif test ${TARGET} = "pylint";
+		elif test ${TARGET} = "lint_and_type_check";
 		then
-			DPKG_PACKAGES="${DPKG_PACKAGES} python3-distutils pylint";
+			DPKG_PACKAGES="${DPKG_PACKAGES} pylint python3-distutils python3-mypy";
 		fi
 		if test "${TARGET}" != "jenkins3";
 		then

config/travis/run_pylint.sh → config/travis/run_checks.sh

@@ -1,12 +1,14 @@
 #!/bin/bash
 #
-# Script to run pylint on Travis-CI.
+# Script to run lint and type checks on Travis-CI.
 #
 # This file is generated by l2tdevtools update-dependencies.py, any dependency
 # related changes should be made in dependencies.ini.
 
-# Exit on error.
-set -e;
+EXIT_SUCCESS=0;
+EXIT_FAILURE=1;
+
+RESULT=${EXIT_SUCCESS};
 
 pylint --version
 
@@ -19,4 +21,20 @@ do
 	echo "Checking: ${FILE}";
 
 	pylint --rcfile=.pylintrc ${FILE};
+
+	if test $? -ne ${EXIT_SUCCESS};
+	then
+		REUSLT=${EXIT_SUCCESS};
+	fi
 done
+
+mypy --version
+
+mypy --strict dfdatetime tests;
+
+if test $? -ne ${EXIT_SUCCESS};
+then
+	REUSLT=${EXIT_SUCCESS};
+fi
+
+exit ${RESULT};

config/travis/runtests.sh

@@ -17,9 +17,9 @@ then
 	then
 		TEST_COMMAND="tox -e ${TOXENV}";
 
-	elif test "${TARGET}" = "pylint";
+	elif test "${TARGET}" = "lint_and_type_check";
 	then
-		TEST_COMMAND="./config/travis/run_pylint.sh";
+		TEST_COMMAND="./config/travis/run_checks.sh";
 	else
 		TEST_COMMAND="./config/travis/run_python3.sh";
 	fi
@@ -51,9 +51,9 @@ then
 	then
 		TEST_COMMAND="./config/jenkins/linux/run_end_to_end_tests_py3.sh travis";
 
-	elif test "${TARGET}" = "pylint";
+	elif test "${TARGET}" = "lint_and_type_check";
 	then
-		TEST_COMMAND="./config/travis/run_pylint.sh";
+		TEST_COMMAND="./config/travis/run_checks.sh";
 	else
 		TEST_COMMAND="./config/travis/run_python3.sh";
 	fi

dfdatetime/apfs_time.py

@@ -4,6 +4,7 @@
 from __future__ import unicode_literals
 
 import decimal
+import typing
 
 from dfdatetime import definitions
 from dfdatetime import posix_time
@@ -19,14 +20,14 @@ class APFSTime(posix_time.PosixTimeInNanoseconds):
     is_local_time (bool): True if the date and time value is in local time.
   """
 
-  def _GetNormalizedTimestamp(self):
+  def _GetNormalizedTimestamp(self) -> typing.Union[decimal.Decimal, None]:
     """Retrieves the normalized timestamp.
 
     Returns:
       decimal.Decimal: normalized timestamp, which contains the number of
-          seconds since January 1, 1970 00:00:00 and a fraction of second used
-          for increased precision, or None if the normalized timestamp cannot be
-          determined.
+          seconds since January 1, 1970 00:00:00 and a fraction of second
+          used for increased precision, or None if the normalized timestamp
+          cannot be determined.
     """
     if self._normalized_timestamp is None:
       if (self._timestamp is not None and self._timestamp >= self._INT64_MIN and
@@ -37,7 +38,7 @@ def _GetNormalizedTimestamp(self):
 
     return self._normalized_timestamp
 
-  def CopyFromDateTimeString(self, time_string):
+  def CopyFromDateTimeString(self, time_string: str) -> None:
     """Copies a APFS timestamp from a date and time string.
 
     Args:
@@ -58,7 +59,7 @@ def CopyFromDateTimeString(self, time_string):
         self._timestamp > self._INT64_MAX):
       raise ValueError('Date time value not supported.')
 
-  def CopyToDateTimeString(self):
+  def CopyToDateTimeString(self) -> typing.Union[str, None]:
     """Copies the APFS timestamp to a date and time string.
 
     Returns:

dfdatetime/cocoa_time.py

@@ -4,6 +4,7 @@
 from __future__ import unicode_literals
 
 import decimal
+import typing
 
 from dfdatetime import definitions
 from dfdatetime import interface
@@ -12,7 +13,7 @@
 class CocoaTimeEpoch(interface.DateTimeEpoch):
   """Cocoa time epoch."""
 
-  def __init__(self):
+  def __init__(self) -> None:
     """Initializes a Cocoa time epoch."""
     super(CocoaTimeEpoch, self).__init__(2001, 1, 1)
 
@@ -36,28 +37,29 @@ class CocoaTime(interface.DateTimeValues):
 
   _EPOCH = CocoaTimeEpoch()
 
-  def __init__(self, timestamp=None):
+  def __init__(self, timestamp: typing.Optional[float] = None) -> None:
     """Initializes a Cocoa timestamp.
 
     Args:
       timestamp (Optional[float]): Cocoa timestamp.
     """
     super(CocoaTime, self).__init__()
-    self._precision = definitions.PRECISION_1_SECOND
-    self._timestamp = timestamp
+    self._precision: str = definitions.PRECISION_1_SECOND
+    self._timestamp: typing.Union[float, None] = timestamp
 
   @property
-  def timestamp(self):
+  def timestamp(self) -> typing.Union[float, None]:
     """float: Cocoa timestamp or None if timestamp is not set."""
     return self._timestamp
 
-  def _GetNormalizedTimestamp(self):
+  def _GetNormalizedTimestamp(self) -> typing.Union[decimal.Decimal, None]:
     """Retrieves the normalized timestamp.
 
     Returns:
-      float: normalized timestamp, which contains the number of seconds since
-          January 1, 1970 00:00:00 and a fraction of second used for increased
-          precision, or None if the normalized timestamp cannot be determined.
+      decimal.Decimal: normalized timestamp, which contains the number of
+          seconds since January 1, 1970 00:00:00 and a fraction of second
+          used for increased precision, or None if the normalized timestamp
+          cannot be determined.
     """
     if self._normalized_timestamp is None:
       if self._timestamp is not None:
@@ -66,7 +68,7 @@ def _GetNormalizedTimestamp(self):
 
     return self._normalized_timestamp
 
-  def CopyFromDateTimeString(self, time_string):
+  def CopyFromDateTimeString(self, time_string: str) -> None:
     """Copies a Cocoa timestamp from a date and time string.
 
     Args:
@@ -92,19 +94,19 @@ def CopyFromDateTimeString(self, time_string):
     microseconds = date_time_values.get('microseconds', None)
     time_zone_offset = date_time_values.get('time_zone_offset', 0)
 
-    timestamp = self._GetNumberOfSecondsFromElements(
+    number_of_seconds = self._GetNumberOfSecondsFromElements(
         year, month, day_of_month, hours, minutes, seconds, time_zone_offset)
-    timestamp += self._COCOA_TO_POSIX_BASE
+    number_of_seconds += self._COCOA_TO_POSIX_BASE
 
-    timestamp = float(timestamp)
+    timestamp = float(number_of_seconds)
     if microseconds is not None:
       timestamp += float(microseconds) / definitions.MICROSECONDS_PER_SECOND
 
     self._normalized_timestamp = None
     self._timestamp = timestamp
     self._time_zone_offset = time_zone_offset
 
-  def CopyToDateTimeString(self):
+  def CopyToDateTimeString(self) -> typing.Union[str, None]:
     """Copies the Cocoa timestamp to a date and time string.
 
     Returns:

dfdatetime/decorators.py

@@ -4,12 +4,19 @@
 from __future__ import unicode_literals
 
 import warnings
+import typing
 
 
-def deprecated(function):  # pylint: disable=invalid-name
+# pylint: disable=invalid-name
+RETURN_TYPE = typing.TypeVar('RETURN_TYPE')
+
+
+def deprecated(function: typing.Callable[..., RETURN_TYPE]) -> typing.Callable[
+    ..., RETURN_TYPE]:
   """Decorator to mark functions or methods as deprecated."""
 
-  def IssueDeprecationWarning(*args, **kwargs):
+  def IssueDeprecationWarning(
+      *args: typing.Any, **kwargs: typing.Any) -> RETURN_TYPE:
     """Issue a deprecation warning."""
     warnings.simplefilter('default', DeprecationWarning)
     warnings.warn('Call to deprecated function: {0:s}.'.format(

dfdatetime/delphi_date_time.py

@@ -4,6 +4,7 @@
 from __future__ import unicode_literals
 
 import decimal
+import typing
 
 from dfdatetime import definitions
 from dfdatetime import interface
@@ -12,7 +13,7 @@
 class DelphiDateTimeEpoch(interface.DateTimeEpoch):
   """Delphi TDateTime epoch."""
 
-  def __init__(self):
+  def __init__(self) -> None:
     """Initializes a Delphi TDateTime epoch."""
     super(DelphiDateTimeEpoch, self).__init__(1899, 12, 30)
 
@@ -38,29 +39,29 @@ class DelphiDateTime(interface.DateTimeValues):
 
   _EPOCH = DelphiDateTimeEpoch()
 
-  def __init__(self, timestamp=None):
+  def __init__(self, timestamp: typing.Optional[float] = None) -> None:
     """Initializes a Delphi TDateTime timestamp.
 
     Args:
       timestamp (Optional[float]): Delphi TDateTime timestamp.
     """
     super(DelphiDateTime, self).__init__()
-    self._precision = definitions.PRECISION_1_MILLISECOND
-    self._timestamp = timestamp
+    self._precision: str = definitions.PRECISION_1_MILLISECOND
+    self._timestamp: typing.Union[float, None] = timestamp
 
   @property
-  def timestamp(self):
+  def timestamp(self) -> typing.Union[float, None]:
     """float: Delphi TDateTime timestamp or None if timestamp is not set."""
     return self._timestamp
 
-  def _GetNormalizedTimestamp(self):
+  def _GetNormalizedTimestamp(self) -> typing.Union[decimal.Decimal, None]:
     """Retrieves the normalized timestamp.
 
     Returns:
       decimal.Decimal: normalized timestamp, which contains the number of
-          seconds since January 1, 1970 00:00:00 and a fraction of second used
-          for increased precision, or None if the normalized timestamp cannot be
-          determined.
+          seconds since January 1, 1970 00:00:00 and a fraction of second
+          used for increased precision, or None if the normalized timestamp
+          cannot be determined.
     """
     if self._normalized_timestamp is None:
       if self._timestamp is not None:
@@ -70,7 +71,7 @@ def _GetNormalizedTimestamp(self):
 
     return self._normalized_timestamp
 
-  def CopyFromDateTimeString(self, time_string):
+  def CopyFromDateTimeString(self, time_string: str) -> None:
     """Copies a Delphi TDateTime timestamp from a string.
 
     Args:
@@ -99,10 +100,10 @@ def CopyFromDateTimeString(self, time_string):
     if year > 9999:
       raise ValueError('Unsupported year value: {0:d}.'.format(year))
 
-    timestamp = self._GetNumberOfSecondsFromElements(
+    number_of_seconds = self._GetNumberOfSecondsFromElements(
         year, month, day_of_month, hours, minutes, seconds, time_zone_offset)
 
-    timestamp = float(timestamp) / definitions.SECONDS_PER_DAY
+    timestamp = float(number_of_seconds) / definitions.SECONDS_PER_DAY
     timestamp += self._DELPHI_TO_POSIX_BASE
     if microseconds is not None:
       timestamp += float(microseconds) / definitions.MICROSECONDS_PER_DAY
@@ -111,7 +112,7 @@ def CopyFromDateTimeString(self, time_string):
     self._timestamp = timestamp
     self._time_zone_offset = time_zone_offset
 
-  def CopyToDateTimeString(self):
+  def CopyToDateTimeString(self) -> typing.Union[str, None]:
     """Copies the Delphi TDateTime timestamp to a date and time string.
 
     Returns: